Is this what you mean?
Wide
The control is wide enough here -
http://www.daypilot.org/files/3.1/bugs/communications-wide.gif
All the columns and header correspond.
Narrow
The control is too narrow -
http://www.daypilot.org/files/3.1/bugs/communications-narrow.gif
"Communications" text of the header is always visible and the column widths don't correspond.
It happens when you have too long word in the header and when the control is too narrow at the same time.
I'll try to tweak the header cell not to show all the text when there is not enough space there.